<研究論文>窒素およびメタンをプローブとする天然ゼオライトの吸着特性

概要

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Adsorption isotherms of nitrogen and methane were measured on natural clinoptilolite andmontmorillonite/mordenite zeolites as adsorbents, IR spectra of methane adsorbed by the naturalzeolites were also measured. Analyses of isotherms of nitrogen showed that small surface area(SEET ; 20~26m2g-1) and pore volume (Vp ; O.060~O.062mlg-l) as well as small micro porosity (internalsurface area, SINT; 3~4m2g-" micro pore volume, Vmiceo ; O.008~O.0l1mlg-l), while those of largervalues (SEET; 112m'g', Vp ; O.24mlg" SINT ; 17m'g-" Vmice, ; O.048mlg ') for montmorillonite/mordenitezeolite. Adsorption data of methane on clinoptilolite zeolites and on montmorillonite/mordenitezeolite were not found to obey a Langmuir-type adsorption equation even in the range of lowerpressures (p <200mmHg). Isosteric heats of adsorption (q,t) of methane on montmorillonite/mordenite zeolite were larger than those on clinoptilolite zeolites. The values of q,t decreased withan increase in the amount of methane adsorbed, indicating that surfaces of the natural zeolites arenot homogeneous and adsorption of methane is likely to proceed on stronger adsorption sites. IRspectra of the J) l.CH" for the natural zeolites-methane system suggested that methane molecules areadsorbed on strong cationic sites which corresponds to Na~ and K+ sites for clinoptilolite zeolitesand to Ca2+ and Na+ sites for montmorillonite/mordenite zeolite.
秋田大学の論文